1. Field of the Invention
This invention relates generally to adaptive optics systems and, more particularly, to object acquisition and alignment of adaptive optics systems.
2. Description of the Related Art
With recent advances in technology, there is an increasing interest in the use of adaptive optics for various applications. For example, there is a rapidly expanding need for data transmission and an infrastructure to accomplish it. While the use of fiber optics has increased the capacity and efficiency of data transmission, the expanding data transmission needs require continual additions to the fiber optics infrastructure at enormous expense and difficulty. There have been experiments and attempts to augment the data transmission system by using light waves through the free-space of the atmosphere. However, the inevitable changes in atmospheric conditions are a significant impediment to the accuracy and reliability of free space optical data transmission systems. For example, atmospheric conditions such as wind, heat waves and the like create aberrations that are constantly changing. This, in turn, degrades the quality of the wavefront that is received, resulting in degradation of the overall quality of the data transmission. There is an increasing interest to use adaptive optics to correct for these aberrations, thus improving the performance and reliability of free space optical data transmission systems.
However, for certain applications, it can be difficult to align the adaptive optics system. For example, in data transmission applications, it is usually desirable for the transmitter to generate a narrow optical beam in order to increase the power efficiency of the system. The receiver optics typically also has a narrow field of view in order to avoid receiving unnecessary background noise and undesirable artifacts. However, it is generally difficult to align a receiver with a narrow field of view to a transmitted beam which is also narrow in beam width.
Increasing the width of the transmitted optical beam and/or the field of view of the receiver optics can reduce this difficulty. However, both of these solutions have significant drawbacks. As mentioned above, increasing the width of the transmitted optical beam means that a greater percentage of the beam will not be collected by the receiver optics and will be wasted, lowering the overall efficiency of the system. In addition, if multiple receivers are located close to one another, a transmitted optical beam that is wider than the collection aperture of the receiver optics may spill over to adjacent receivers, interfering with their proper operation. Increasing the field of view of the receiver optics also has its drawbacks. In addition to collecting more background noise, increasing the field of view increases the chances that auto-tracking receivers will track the wrong object. Adaptive optics systems typically run in closed loop mode where they automatically correct for the aberrations experienced by an object—the transmitted optical beam in this example. However, systems may sometimes begin to track the wrong object, for example the sun, glints, or other bright objects that appear within the system's field of view. Increasing the field of view increases the risk that this might happen.
Thus, there is a need for adaptive optics imaging systems that have improved acquisition and alignment capability.